NexGen Nx586

Intel dominated the CPU business and always had until then. Despite the fact that the 486 was cloned by more manufacturers than ever. The original design was done by Intel, which meant that royalties had to be paid for every cloned 486 produced. Some manufacturers designed their own 486 for instance Cyrix and IBM. But these were never sold in the same quantities as Intel's 486 design. The monopolistic position of Intel also meant that it could keep prices high. PC manufacturers however had no real alternative than to buy their CPU's from Intel.

The race was on for the next generation CPU after the 486. Intel was very busy with the design of the Pentium. Other companies like Cyrix and AMD were also designing their next generation CPU's. They were however lagging behind.
Compaq was the largest PC manufacturer at that time and it wanted a real alternative to Intel or maybe just a way to get the pressure on Intel. So they financially backed a new promising CPU design company : NexGen microsystems.

Nexgen Inc. was founded by Thampy Thomas in 1986. Its goal at that time was to design a 386 competitor, not an Intel clone but a new x86 compatible design. Apparently from the start the design would incorporate CISC and RISC elements. Talented engineers like Mack McFarland, Dave Stiles, Greg Favor and Korbin Van Dyke worked on the design and implementation.
Unfortunately the team faced many issues and delays. For instance, one of the first designs was so large that it ended up in 8 PGA's the size of a standard 386. By the time the design was ready, the 386 was history, the 486 was the CPU to have and the next generation chips were already on the drawing tables at Intel, AMD and Cyrix.

Finally after eight years of hard working on the CPU with the codename F86, Nexgen announced to the world the Nx586 in March 1994. Although it was fully compatible with the i386 instruction set, the design was far more advanced. The Nx586 could process two instructions in one clock cycle (superscalar) and had 32KB L1 cache (16KB instruction & 16KB data). But many more new technologies were incorporated in the design like advanced branch prediction and 64bit busses. Something else Nexgen pioneered was the inclusion of the L2 cache controller in the CPU, this allowed for much faster L2 cache access. But the most famous feature was the RISC86 microarchitecture.

RISC86 was the name of the solution Nexgen used to execute RISC instructions in a CISC environment. The instructions that are fetched from memory are standard x86 instructions, but the instructions executed in the processing pipelines are RISC-like translations of the CISC x86 instructions. NexGen calls them RISC86 instructions and these give the Nx586, Pentium-class performance.

Nexgen announced the Nx586 CPU and the Nx587 coprocessor at speeds of 60MHz and 66MHz. The floating point processor was designed as a separate chip as was common in the 386 days. If you needed one you could buy it and plug it in a special socket on the motherboard. The CPU was not pin-compatible with any of Intel's CPU, it had 463 pins and used Nexgen's own NxVL chipset. As a reference, the Intel Pentium had 296 pins.
Prices were set at $460 for the 60MHz version, $506 for the 66MHz version and $128 for Nx587. As a reference, Intel's Pentium 60 and 66 sold for $675 and $750 respectively. However production of the Nx586 and Nx587 was not yet started. IBM was contracted for the production of the samples but no volume production deal was made at that time.

Having a newly designed CPU is great, but it has to be sold. The Nexgen marketing department was very busy gaining support in the PC business for the Nx586. By april Nexgen announced deals with 11 PC manufacturers in the US and Taiwan. Many new manufacturers and OEM distributors followed later in 1994, but no major player like Compaq, IBM or Dell could be contracted to use the Nx586 in their systems.

On June 13 Nexgen, at last, announced a foundering deal with IBM. The 3.5million transistor Nx586 and the 700.000 transistor Nx587 would be manufactured using IBM's CMOS 5Lprocess. The technology produced 0.5 micron CMOS silicon with 5 layer metal interconnect on 8 inch wafers. IBM would also package the CPU and FPU cores using its own C4 'flip chip' technology. With this deal volume production could be started and shipping date was set for Q4 of that year.

Nexgen designed its own chipset for the Nx586 with the help of VLSI. The first chipset was the NxVL for motherboards equipped with a VESA Local Bus. This chipset was manufactured by Fujitsu and was packaged in a Ceramic PGA, very unusual.
Nexgen intended to realease a PCI chipset, the NxPCI (820C500), by fall 1994. But the chipset design was troublesome and it was delayed many times. Finally the combined Nexgen/VLSI design team got it together and it arrived to market in September 1995, one year late! At the end of 1994 Nexgen also announced its plans for a cost reduced version of the NxVL chipset. The NxVL2, which would be able to support the Nx586 and the next generation CPU Nx686. This chipset however was never released.

In September 1994 NexGen was ready to begin volume shipments of its Nx586. By that time the x86 processor landscape had changed drastically. Intel had released the Pentium and clock speeds were already up to 100MHz. Nexgen changed its strategy for its CPU and introduced a range of speed grades : Nx586-P75, Nx586-P80, Nx586-P90 and the Nx586-P100. The initial speeds of 60MHz and 66MHz announced in March 1994 were never released. Also the Nx587 would never be released, the two socket solution turned out to be impractical. Instead Nexgen announced that it would release a Nx586 with a Nx587 in one multichip module (MCM) package.

Nexgen got a lot of media attention with the release of its CPU. Of all the CPU manufacturers they were the first to introduce a real competitor to the Intel Pentium. Cyrix was finishing the M1 (6x86) and AMD was still trying to get their K5 to work properly. Was the Nx586 going to be a Pentium killer as many hoped it would be? After much testing by many peaople the answer to that question was a little disappointing. The Nx586 performed very well, but not better than the Pentium.
However, the Nx586 was running at lower speeds than comparable Pentiums. Nexgen gave their chips a P-rating, this rating was to indicate which performance a particular Nx586 had relative to a Pentium. A Nx586 P90 had roughly the same performance as a Pentium 90MHz. However the clockspeed of a Nx586 P90 was only 84MHz. So on a clock for clock basis the performance was superior.

With a big player like Intel, getting a foothold in the processor business is hard. To gain the buyers attention continues price drops had to be made. By the time the Nx586 was actually for sale, the entry Nx586-P75 cost $404, the P80 $477, $539 for the P90 and the P100 was priced at $777. With new price cuts in mind Nexgen sought ways to reduce costs. One way was to make production of the Nx586 more efficient, fit more die's on a wafer. Around May 1995 Nexgen announced a die shrink for its CPU, one month later more details appeared. The die size was reduced about 40% from 192mm2 to 118mm2 while still using IBM's 0.5 micron CMOS 5L process. This design change made it possible to increase the number of die's per wafer from 112 to 199.

The Nx586 processor itself did not support the CPUID feature, the BIOS of the motherboard could load that microcode. Unfortunately this did not work with the older BIOS's. The only way to be sure what speedgrade the CPU had was the print on the processor itself or looking for the jumpers J3 (NxVL) or J9-J10-J11 (NxPCI) on the motherboard. However, some software wanted to know what CPU it had to work with. Windows95 for instance would not install on a Nexgen system. To 'fool' Windows Nexgen released a small program (IDON.COM) which tells the windows CPU detection routine that the Nx586 is a 586 class CPU. Later models, the P120 and P133, would incorporate the CPUID feature.

Compaq backed Nexgen financially since 1990, but had never used the Nx586 for its PC's. But in April 1995 Compaq announced it would introduce desktop PC's built around Nexgen's 586-class microprocessor. This was a Nexgen's first design-win with a top-tier PC maker and it hoped more would follow.
Compaq wasn't comfortable with Nexgen having only IBM as foundry partner. Promptly Nexgen announced it would make a deal with another foundry partner by the end of the year.

Nexgen discontinued its Nx586 P75 and P80 around August 1995. Demand had shifted to higher performance parts and NexGen needed the capacity for the imminent rollout of its new P120 and P133. These new speeds were manufactured with IBM's new CMOS 5S process at 0.44 micron. Prices were once again reduced from $299 to $245 for the P90 and from $399 to $340 for the P100.
In the mean time Nexgen was still trying to close additional deals for the manufacturing of motherboards and chipsets. To date motherboards were only manufactured by Alaris and chipsets by Fujitsu.

The first NxPCI AT motherboards were shipped at the beginning of September 1995 after they were first announced in fall 1994. Motherboards featured support for EDO and Fast Page memory up to 768MB DRAM, up to four IDE devices, an on-board floppy controller, two serial ports and one parallel. It had four ISA slots and three PCI slots. Prices for a complete configuration, motherboard, CPU and heatsink were at $339 in combination with the Nx586 P90 and $439 with a P100.

At the eights annual Microprocessor Forum conference in October Nexgen gave the world a first look at its next generation processor, the Nx686. It was introduced as a direct competitor to Intel's Pentium Pro. The Nx686 would have 6.5 million transistors, almost double the amount of the Nx586. Introduction speed would be 180MHz and IBM would manufacture the Nx686 with its advanced five-layer CMOS process at 0.35 micron. The future looked bright for Nexgen, it expected to announce a new manufacturing partner soon and Samsung was contracted for the production of chipsets.

Then, on October the 30 1995, AMD announced its intention to take over Nexgen for about $850 million. AMD had troubles to get its 586 class CPU, the K5, to market and would get an almost ready 686 class chip in house. The merger of NexGen with AMD was formalized on January 17 1996.

For over a year now Nexgen was shipping FPU less Nx586's, but this was about to end. In November 1995 Nexgen announced the Nx586 with integrated FPU, the Nx586 Pf100 and the faster Nx586 Pf120. The CPU and FPU would packaged together on a Multichip Module and manufactured by IBM. The Nx586 Pf100 would be available in December and the Pf120 was scheduled for Q1 1996.

After the merger with AMD things got quiet around Nexgen and the Nx586. No new speeds were announced, no new customers or distributers, nothing.
Not really a fitting end to a CPU with so many new technologies. But in the end it is all about the money. Unfortuantely the fact that the Nx586 needed a proprietary motherboard slowed down user adaptation. Sales were just not good enough to make the Nx586 a success.

When AMD took over Nexgen they changed the Nx686 design to make it compatible with Intel's platforms. This resulted in the K6 which became a good selling CPU for AMD. The fact that you could use it in combination with many different motherboards that were available made it an option for more people.

Nx586 P75, 70MHz, 2 x 35MHz
Nx586 P80, 75MHz, 2 x 37.5MHz
Nx586 P90, 84MHz, 2 x 42MHz
Nx586 P100, 93MHz, 2 x 46.5MHz
Nx586 P110, 102MHz, 2 x 51MHz
Nx586 P120, 111MHz, 2 x 55.5MHz

Nx586 PF100, 93MHz, 2 x 46.5MHz
Nx586 PF110, 102MHz, 2 x 51MHz

Memotech.Franken.de : Information about the Nx586 motherboards, the BIOS and the CPU itself.
AMD Nexgen :
Google search on Nexgen Nx586